The performance of many implanted biomedical devices is dependent on the surface characteristics of the implant material. Hydrogel coatings are now being developed and used by investigators to lower the thrombogenicity and immunogenicity of these devices, phenomena that are usually initiated by the adsorption of body fluid proteins on the implant. Improvement of tribological properties is also important in orthopedic devices, almost all of which involve sliding articulations between two surfaces. For example, an artificial joint often involves the combination of metal and plastic. In a total knee replacement, a metal component is attached to the femur, which, upon flexion, glides over a plastic bearing connected to a metal base that is attached to the top of the tibia. Artificial vertebral discs available for human use today involve variations of metal-on-plastic or plastic-on-plastic gliding articulations between components sandwiched between two vertebrae. A total hip replacement device usually contains a metallic implant with a “ball” on its end that sits within a shell implanted inside the pelvic “socket” (the acetabulum). There are also similar prostheses used to partially (i.e. hemi-arthroplasty) or totally (i.e. total arthroplasty) replace or resurface other joints such as the shoulder and ankle and the joints in the hands and feet. In prosthetic joint applications, the most commonly used metals are titanium and cobalt chrome while the most commonly used plastic is polyethylene. Unfortunately, the use of plastics in orthopedic prostheses has several disadvantages, including rigidity, wear, and low biocompatibility compared to biological solutions. Other materials such as ceramics are now being developed and used in these devices as alternative bearing materials to metals and polymers. Accordingly, there is a need in the art to develop new materials for orthopedic and medical devices that would at least overcome some of these disadvantages. The present invention addresses these needs and provides devices based on hydrogel-metal assemblies.